100 lines
2.1 KiB
C++
100 lines
2.1 KiB
C++
#include <array>
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#include <bit>
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#include <cstdint>
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#include <iostream>
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#include <optional>
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#include <string>
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#include <vector>
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#include <doctest.h>
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#include <aocpp/Startup.hpp>
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#include <aocpp/Parsing.hpp>
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namespace {
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/*
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\ n /
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nw +--+ ne
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/ \
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-+ +-
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\ /
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sw +--+ se
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/ s \
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*/
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struct Hex {
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std::int64_t q, r, s;
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};
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constexpr Hex HEX_N { 0, -1, 1 };
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constexpr Hex HEX_NE { 1, -1, 0 };
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constexpr Hex HEX_SE { 1, 0, -1 };
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constexpr Hex HEX_S { 0, 1, -1 };
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constexpr Hex HEX_SW { -1, 1, 0 };
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constexpr Hex HEX_NW { -1, 0, 1 };
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auto operator+(Hex a, Hex b) -> Hex {
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return {a.q + b.q, a.r + b.r, a.s + b.s };
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}
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auto operator+=(Hex & a, Hex b) -> Hex & {
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a.q += b.q; a.r += b.r; a.s += b.s;
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return a;
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}
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auto hex_distance(Hex hex) -> std::int64_t {
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return (std::abs(hex.q) + std::abs(hex.r) + std::abs(hex.s)) / 2;
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}
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auto Walk(std::string const& commands)
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-> std::pair<std::int64_t, std::int64_t>
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{
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Hex here {};
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std::int64_t part2 = 0;
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for (auto const& command : aocpp::SplitOn(commands, ",")) {
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here +=
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"n" == command ? HEX_N :
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"ne" == command ? HEX_NE :
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"nw" == command ? HEX_NW :
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"s" == command ? HEX_S :
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"se" == command ? HEX_SE :
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"sw" == command ? HEX_SW :
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throw std::runtime_error{"bad input"};
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part2 = std::max(part2, hex_distance(here));
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}
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return {hex_distance(here), part2};
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}
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} // namespace
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TEST_SUITE("2017-11 examples") {
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TEST_CASE("example 1") {
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auto [p1,p2] = Walk("ne,ne,ne");
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CHECK(p1 == 3);
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CHECK(p2 == 3);
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}
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TEST_CASE("example 2") {
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auto [p1,p2] = Walk("ne,ne,sw,sw");
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CHECK(p1 == 0);
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CHECK(p2 == 2);
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}
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TEST_CASE("example 3") {
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auto [p1,p2] = Walk("ne,ne,s,s");
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CHECK(p1 == 2);
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CHECK(p2 == 2);
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}
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TEST_CASE("example 4") {
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auto [p1,p2] = Walk("se,sw,se,sw,sw");
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CHECK(p1 == 3);
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CHECK(p2 == 3);
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}
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}
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auto main(int argc, char** argv) -> int {
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std::string line;
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std::getline(*aocpp::Startup(argc, argv), line);
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auto [part1, part2] = Walk(line);
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std::cout << "Part 1: " << part1 << std::endl;
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std::cout << "Part 2: " << part2 << std::endl;
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} |